Electrolytic lathe



Dec. 21, 1965 Filed April '7. 1961 J. D. RUSSELL 3,224,953

ELECTROLYTIC LATHE 6 Sheets-Sheet 1 s: 1 l (kw if @A INVENTOR JOHN D.QUSSELL ATTORNEY Dec. 21, 1965 J D. RUSSELL 3,224,953

ELECTROLYTIC LATHE Filed April 7, 1961 6 Sheets-Sheet 2 MOTOR RaverzsmeCIRCLHT 1 MQZO IN VENTOR 1 JOHN D. Dussau. F1G.G L2 BY ATTORNEY Dec. 21,1965 J. D. RUSSELL 3,224,953

ELECTROLYTIC LATHE Filed April '7. 1961 6 Sheets-Sheet 4 I (I 2 3 7/ 5I3 P4 22 9 64 74 /R3 R2 ;-1 73 78 72 C2 86 c3 7 f 68 7o 8 W m QAMFLIFIERFIG. l4

INVENTOR JOHN D. RUSSELL.

ATTORNEY United States Patent 3,224,953 ELEQTROLYTIC LATHE John D.Russell, Malibu, Calif., assignor to Microdot Inc, Pasadena, Calif., acorporation of Caiifornia Filed Apr. 7, 1961, Ser. No. 103,135 Claims.((11. 204-212) This invention relates to apparatus for and method ofelectrolytically treating elongated metallic articles with a movingstream of liquid for the purpose of shaping the same as desired. Thisapplication is a continuation-inpart of my copending application SerialNo. 669,144, filed July 1, 1957, now abandoned.

While, more specifically, the article to be treated in accordance withthe invention constitutes an electrode of an electric circuit, and theliquid is an electrolyte, the invention includes, in its broaderaspects, the treatment of elongated articles of any kind of material byany kind of a liquid which will either act upon them to change theirshape or profile, or serve simply for washing or cleaning purposes. Insuch treatment, the invention contemplates causing a continuouslyflowing sheet or film of liquid to impinge upon the article, whilerelative movement is produced between the sheet and the article,longitudinally of the latter.

The electrolytic embodiment of the invention, as above mentioned, findsspecial utility in the production of metal rods or wires, such forexample as the wires used in the manufacture of resistance strain gages.Such wires comprise a main body of very small diameter connected at itsends to leads or terminals of much larger diameter, and an effectivemethod of joining such leads to the main body has long been sought. Aspecific object of the present invention is to provide a convenientmeans for the production of a true one-piece wire gage element, by whichthe problem of forming a proper joint may be eliminated.

While particularly well adapted to the production of strain gage wires,the invention is of course equally applicable to the manufacture of anywire elements in which a fine body is joined to heavier lead Wires, as,for example, in rheostats, potentiometers, etc.

In practice, manufacture is accomplished by starting with a piece ofrelatively large wire and, by means of the invention, reducing thediameter of the central portion to the desired extent.

A further specific object of the invention is to provide an improvedapparatus and method of making what I call a high sensitivity gageelement, namely a wire formed in one piece and having sections ofalternately large and small diameter.

While, of course, the production of rods or bars having portions ofdifferent diameters by means of an ordinary lathe presents no problem,so far as I am aware no method has heretofore been devoloped forproducing cylindrical elements having portions of different diameterswhere the element is in the nature of a fine wire. By the use of thepresent invention, wires down to .0005 in diameter can be successfullyoperated upon.

In order that the invention may be readily understood, reference is hadto the accompanying drawings, forming part of this specification, andillustrating, by way of example, certain apparatus embodying theinvention and by which the method of the invention can be carried out.In these drawings:

FIG. 1 is an elevational view of the portion of a strain gage wire whichcan be produced in accordance with the present invention;

FIG. 2 is a schematic diagram of one embodiment of apparatus by whichthe method of the present invention can be practiced;

FIG. 3 is a view in perspective of an embodiment of means forestablishing a thin film or sheet of liquid in contact with an elongatedelement to be treated in accordance with the invention;

FIG. 4 is a plan view, partially schematic, illustrating certainportions of apparatus embodying the invention;

FIG. 5 is a sectional view taken on line 55, FIG. 4, with some partsshown in end elevation;

FIG. 6 is a schematic view illustrating one mode of operation of theapparatus of FIG. 4;

FIG. 7 is an elevational view of a portion of a typical product producedin accordance with the invention along with a comparative illustrationof a control element useful in the apparatus of FIG. 4 for producingsuch product;

FIG. 8 is an elevational view, similar to FIG. 1, of another product ofthe invention;

FIG. 9 is a diagrammatic illustration of means by which the product ofFIG. 8 can be continuously produced;

FIG. 10 is a view, similar to FIG. 7, illustrating the product of theinvention shown in FIG. 8 and a coextensive control element useful inproducing the same;

FIG. 11 is a view in perspective, partially schematic, illustratinganother form of control device which can be used in place of that shownin FIG. 10;

FIG. 12 is a schematic diagram of a further embodi ment of theinvention;

FIG. 13 is a view somewhat similar to FIG. 6, showing a slightlymodified circuit arrangement;

FIG. 14 is a diagrammatic view illustrating, by way of example, one wayin which the electrolytic action may be automatically controlled inaccordance with any desired electrical resistance which the finishedwire or filament should have;

FIG. 15 is a diagrammatic view illustrating another way in which theelectrolytic action can be automatically controlled in accordance with adimension of the object being shaped;

FIG. 16 is a schematic view illustrating one of the problems whichoccurs when the electrolytic action is controlled in accordance with thediameter of the object being shaped;

FIG. 17 is a view similar to FIG. 16 illustrating one manner in whichthe problem explained with reference to FIG. 16 can be overcome;

FIG. 18 is a diagrammatic view illustrating one way for controlling theelectrodes in the apparatus of FIG. 17;

FIGS. 19 and 20 are elevational views illustrating further embodimentsfor establishing a thin sheet of liquid in contact with the elementbeing treated;

FIGS. 21 and 22 are schematic views illustrating the operation of thedevices of FIGS. 19 and 20 respectively;

FIG. 23 is a schematic view, partly in section, illustrating anothermanner of applying the electrolytic liquid to the article being treated;

FIG. 24 is a schematic view, partly in section, illustrating another wayin which the electrolytic action can be automatically controlled inaccordance with a dimension of the article being treated;

FIG. 25 is a schematic plan View illustrating apparatus forautomatically reversing the movement of the carriage;

FIG. 26 is a schematic plan view illustrating another embodiment ofapparatus for moving a plurality of articles being treated;

FIG. 27 is an end elevational view, partly in section, along lines2'7--27 of FIG. 26; and

FIG. 28 is a block diagram illustrating one way in which theelectrolytic lathe can be automatically operated.

Referring to the drawings in detail and more particularly first to FIGS.1 to 3 thereof, 1 represents the main portion of a strain gage, whilethe leads at each end are indicated at 1 By way of example, it may beexplained that such strain gages are usually constructed of Nichromewire having a diameter of approximately .0007 of an inch, with the leadshaving a diameter of around .006 of an inch.

While the present invention is of general application and has utility inany art where it is desired to produce a wire or rod having a diameterwhich varies widely at different points in its length, the invention isespecially applicable to the production of the above-mentioned straingage wire.

My improved apparatus for producing a wire of this character may bedescribed as an electrolytic lathe since it embodies some of thecharacteristics of a machine tool of this nature. The inventioncomprises a spreader plate 2 which is preferably downwardly inclined asshown in FIG. 2 and is disposed in a plane transverse to the length ofthe wire 1 being treated. Near the lower end of the plate 2 is formed anopening 3, through which the wire 1 freely passes. A suitableelectrolyte is contained in an elevated tank 4 and is conducted througha conduit 5 including a control valve and a flexible hose 6 to adischarge nozzle at the lower end of this hose. This discharge nozzle isso positioned relative to the plate 2 that the electrolyte issuingtherefrom is delivered onto the inclined plate and is spread thereoninto a thin film or sheet 7 which flows downwardly by gravity along theupper surface of the plate over and across the opening 3. As a result,the portion of the sheet or film defined by the opening 3 isunsupported, but is nevertheless continuous and uninterrupted. Thissheet or film, as it passes over the opening 3, thus impinges againstthe wire 1 which passes through this opening. The sheet or film, as itimpinges against wire 1, lies in a plane which extends transversely ofwire 1. The thickness of the sheet is less than the length of the areabeing treated so that the whole of the area being treated is notsubjected to the electrolytic action at any given time. In this manner,a finer degree of control can be obtained.

The electrolyte discharged from the spreader plate 2 is received in atank 8 from which it is returned by a pump P through pipes 9 and 10 tothe storage tank 4.

A source of direct current such as a battery 11 is provided and one sideof this battery is connected by conductor 12 with the spreader plate 2while the other side is connected by means of a conductor 13 with thewire 1. Thus the sheet of electrolyte flowing along the spreader plate 2and over the opening 3 is connected in a series circuit with the wire 1and battery 11, so that current can flow between the sheet of liquid andthe wire, at the point of contact between such sheet and wire.

Means are provided, as hereinafter more fully explained, for causingrelative movement between the flowing sheet of electrolyte and the wire1, longitudinally of the latter, so that as this relative movement takesplace, the sheet of electrolyte is caused to impinge against successiveportions of the wire.

Means are also preferably provided, as hereinafter described, forrotating the wire at the same time, so that all sides of it will besubjected to the action of the electrolyte.

Thus the piece of wire of the maximum diameter indicated at 1 in FIG. 1may be electrolytically reduced in diameter between any two desiredpoints, by causing a relative movement between the spreader plate andthe wire, the rotation of the wire at the same time insuring theproduction of a wire of truly circular cross section.

Alternatively, if it should be desired to build up or increase thediameter of a fine wire, instead of reducing it, this can beaccomplished by simply reversing the connections of the battery to thewire and spreader plate respectively. In this case, metal will bedeposited or plated upon the wire by means of the electrolyte.

In FIG. 4, I have illustrate-d, more or less diagrammatically, anarrangement of apparatus for automatically carrying out the abovedescribed steps.

In this figure, I have illustrated a pair of chucks 14 between which thewire 1 is stretched and each of which is constructed to grip the end ofthis wire. These chucks are rotated in synchronism by means of suitablegearing, such gearing including gears 15 secured to the chucks, whichmay be made of insulating material such as fiber or plastic, or may bemounted on the chuck shafts by insulating bushings. Meshing with thegears 15 are a pair of pinions 16 secured to a shaft 17 driven by amotor 18. Thus both chucks are driven at exactly the same speed and thewire 1 is thus relieved of any torsional strains.

The pinions 16 are also shown as meshing with a pair of gears 19 securedto the opposite ends of a feed screw 20. Working on this feed screw is acarriage 21, similar to a lathe carriage, and guide rods 22, workingfreely through the carriage are supported by fixed frame members 23through which the feed screw freely passes. The spreader plate 2 ismounted on the carriage 21, as shown in FIGS. 4 and 5. The electricalconnection between the battery 11 and the wire 1 and spreader plate 2 iseffected by means of a contact strip 28 against which bears a contact 27mounted on the carriage 21 and connected with the wire 12 extending fromthe battery. It will be seen that the circuit is completed by means ofthe wire 12 connecting the contact strip 28 with the spreader plate, thechucks 14 being connected with the other side of the battery.

The exact portion of the length of the wire 1 which is subjected to theelectrolytic action is determined by the length of the contact strip 28.As indicated in FIG. 6, this contact strip has a length L which is thesame as that portion of the wire 1 which it is desired to shape. Thecarriage itself may have a traverse such as indicated by the distance Lwhich is much greater than the length of wire which it is desired toshape, but the fact that the contact 27 runs off the contact strip 28 ateach end serves to interrupt the current at these points, and thusprevents any electrolytic action taking place. Thus, although thecarriage and spreader plate may traverse a long length of the wire 1,only the portion of such wire equal in length to that of the contactstrip 23 is subjected to electrolytic action, the portions beyond thedesired length remaining in their original condition, notwithstandingthat the liquid may impinge against them.

The arrangement for interrupting the current at definite points in thelength of the wire 1, as above described, results in the production ofan article such as shown in FIGS. 1 and 6 in which the ends of thetreated wire terminate abruptly in shoulders at the untreated portions.It may be desirable, however, to provide a construction in which theshoulders at the ends of the treated portion of the wire are not abruptbut tapering. This is illustrated in FIG. 7 in which the main body ofthe wire is shown at 1 This effect can be produced by arrangingresistances 29 at each end of the contact strip 28. Thus as the contactor slide 27 rides over these resistances, the current flowing throughthe electrolyte and wire will be gradually reduced, thus producing acorresponding reduction in the amount of etching or electrolytic action.

It will be understood that one of the characteristic features of theinvention, especially when used to produce a finished article such asshown in FIG. 7 is the fact that the electrolytic action takes placeover only a very small area at any one time. In other words, it isstrictly local. This of course results from the fact that the sheet offilm 7 of electrolyte is extremely thin, and impinges edgewise on thewire or other element being treated.

In FIG. 8 I have illustrated what I call a high sensitivity gageelement, namely, a one-piece element having zones or sections ofalternately large and small diameter. The small diameter portions aredesignated by the numeral 1 as before, while the larger diameterportions are indicated at 1 1 and 1 In order to automatically produce anelement having a profile of this kind, I may employ, in place of thecontact strip 28 shown in FIG. 4, a contact strip 28 having thereonspaced sections or segments of insulation, 28*, as shown in FIG. 10. Inthis FIG. I have also reproduced an element similar to that illustratedin FIG. 8, for comparison.

As the slide 27 of FIGS. 5 and 6 moves along this contact strip 28 thecircuit will be completed when the slide engages the metal portions ofthe strip 28 and the circuit will be interrupted when the slide ridesupon the insulated portions 28*. The result is that the electrolytic oretching action takes place while the slide is in contact with theconducting portions of the strip, thus reducing the diameter of the wirefor corresponding portions of its length, as indicated at 1, and whenthe slide is passing over the insulated sections 28*, no electrolytic oretching action takes place and the corresponding portions of the wireretain their original diameter as indicated at 1 and 1 Instead of acommutator of the type shown in FIG. 10, I may employ a rotarycommutator such as illustrated in FIG. 11. As shown in this figure, thiscommutator comprises a metal disc 30 mounted on a shaft which may be thefeed screw of FIG. 4. Oppositely disposed segments 31 of insulatingmaterial are mounted on the face of the disc 30, and a contact brush 32bears upon the face of the disc, this contact brush being connected withthe battery and etching or shaping circuit. As shown, the insulatingsector-shaped segments 31 each extend through approximately 90 so that aconducting surface of the same extent lies between them. In other words,as the disc rotates, the etching or shaping circuit is closed forone-fourth of a revolution and is then interrupted during the nextquarter revolution, etc. This would produce a finished article such asshown in FIG. 8, except that the lengths of the alternately large andsmall sections would be equal.

While in the preceding figures I have illustrated arrangements in whichthe wire is held stationary while the spreader plate and sheet of liquidmove longitudinally thereof, and where relatively short pieces of wireare being treated, one at a time, in FIG. 9 I have illustrated quite adifferent arrangement in which the wire travels while the spreaderplates remain stationary, and long lengths of wire are treatedcontinuously. In this case, the wire is carried by reels 33, so that itis unwound from one and wound upon the other. In order to rotate thewire, as in the preceding figures, the reels 33 themselves must rotatein planes at right angles to the portion of the wire which is beingtreated.

It will be noted that in FIG. 9 I have illustrated a series of spreaderplates 2 through all of which the wire passes successively, and it willbe further noted that some of these spreader plates, as for example thefirst three, are not connected in any way with the electric circuit.These preliminary spreader plates, the nozzles of which may be suppliedwith plain water or any desired cleansing solution, serve merely torinse and wash the wire as it travels along. It will be understood, ofcourse, that although these preliminary spreader plates do not produceany electrolytic action, they do nevertheless provide continuouslyflowing sheets of liquid through which the wire passes, just asdescribed in connection with FIGS. 2 and 3.

Following the rinsing and washing spreader plates I have illustrated aplurality of such plates connected with the electric circuit as beforeand supplied with a suitable electrolyte. By providing a plurality ofspreader plates with their flowing sheets of electrolyte, all of theetching or shaping is not done in a single step but is accomplishedprogressively as the wire passes through successive sheets ofelectrolyte.

In order to continuously produce an article of the desired shape orprofile, such, for example, as that shown in FIG. 8, a suitablecommutator 34, for completing or interrupting the circuit at the propertimes, must be provided. It will also of course be understood that thespacing of the electrolytic spreader plates, as illustrated at the rightin FIG. 9, must be related to the lengths of the alternating small andlarge sections of the Wire produced, and the master commutator 34 willserve to turn the current off and on to all of the spreader platessimultaneously, in proper timed relation, so that etching will takeplace at all of them during the same time intervals, and will beinterrupted at all of them during alternate intervals.

FIG. 12 illustrates a further embodiment of the invention in which theelectrochemical action on the work is controlled directly in response tothe dimension of the work substantially at the point where the Work isbeing treated. In this embodiment of the invention, an optical image ofthe work, such as the wire 1, is projected upon a sheet of ground glass35 by means of light source 36 and lens 37, the image 38 appearing as ashadow on the ground glass. Two photoelectric cells 39 and 40,advantageously of the self-generating type, are arranged to follow therepective edges of the image on ground glass 35. Thus, eachphotoelectric cell 39, 40 can be mounted on a support 41, I

42 adjustable by lead screws 43 and 44 disposed transversely of theground glass 35. Lead screw 43, carrying photoelectric cell 39, isdriven by a servo motor 45 controlled by the photoelectric cell 39through an amplifier 46 and a conventional line follower circuit. Thus,such conventional circuit may be of the type controlling the motor torotate lead screw 43 in one direction in response to a no lightcondition of the photo cell and in the opposite direction in response toa light condition. Similarly, the photoelectric cell 40 is caused tofollow the other edge of the image 38 by means of an identical servomotor 47 and amplifier 49.

Mechanically coupled to the photoelectric cells 39 and 40 are two slidecontacts 50 and 51 respectively, engaging a resistance 52. Theresistance 52 is connected to control the output of an oscillator andamplifier indicated at 53, such output being supplied to a magneticrecorder 54. Thus, the effect of the magnetic recorder is to establish arecord, on any suitable magnetic record medium, indicative of thevarying position of the sliding contacts 50 and 51, and thus indicativeof the positions of the photoelectric cells 39 and 40, and therefore ofthe transverse dimension of the work.

The magnetic record medium is passed continuously through a magneticreproducer 55 and the signal therefrom supplied, through an amplifier 56and a rectifier 57, to the etching or shaping circuit.

By conventional circuit design, the oscillator and amplifier 53 and theamplifier 56 and rectifier 57 are constructed to supply current to theetching circuit only when the value of the resistance between slidecontacts 50 and 51 exceeds a predetermined amount. Thus, etching of thework takes place only as the dimension thereof at any point is in excessof a predetermined value, and, as a result, an article is producedhaving a uniform diameter throughout.

Referring again to FIGS. 2 and 6, it is found that when the current isfed always to one end of the article being shaped there is a tendencyfor the electrolytic action at that end to be excessive or greater thanat the portion adjacent the other end, thus giving rise to anobjectionable lack of uniformity. This variation in the electrolyticaction is due to the resistance of the wire or filament itself. In orderto overcome this, and equalize the action, I may feed the electrolyticcurrent to the article alternately from opposite ends.

An arrangement for doing this is illustrated in FIG. 13 Referring tothis figure, I provide a stationary contact strip 28. This is similar tothe contact strip 28 of FIG. 6, except that it is made /2 the length ofthe article being treated. It is engaged by a contact 27, carried by thespreader plate 2, as before, but in this case this contact and strip,instead of controlling the electrolytic circuit directly, controls thecircuit of a relay. The winding 58 of this relay is connected by wire 13with the spreader plate, and by wire 59 to one side of a source ofcurrent 60, the other side of which is connected by wire 61 with thestrip 28. The winding 58 actuates a pivoted armature 62, urged away fromthe winding by a spring 63, and arranged to play between two fixedcontacts 64 and 65. These contacts are connected by wires 66 and 67 withthe ends 1 and 1 of the article being treated. The armature 62 isconnected to one side of a source of current 11, the other side of whichis connected by wires 12 and 13 with the spreader plate 2.

It will be understood that, as shown in FIG. 13, the contact strip 28terminates at a point midway of the length of the article being treated.Also the contact 27 is shown as in engagement with the strip 28', sothat the relay circuit above traced is closed, the relay is energized,and the armature pulled down into engagement with contact 65.Electrolytic current then flows from source 11 to the end 1 of thearticle, and thence through the article to the spreader plate, and backto the source through wires 13 and 12.

Assuming that, in the position shown in FIG. 13, the spreader plate ismoving from right to left, the contact 27 will, in the next instant,slip off of the strip 28 and thus break the relay circuit. The relay isthereupon deenergized, the spring 63 pulls the armature up intoengagement with the contact 64, and current is then fed from the source11 to the right-hand end 1 of the article. This will continue while thespreader plate moves to the lefthand end of the article, and back againto the middle. When it reaches the middle, the contact 27 will engagethe strip 28' and the electrolytic current will again be fed to theleft-hand end of the article. This will continue while the spreaderplate travels to the right-hand end of the article, and back to themiddle again.

Thus it will be seen that, as the spreader plate reciprocates, currentis fed alternately to opposite ends of the article, shifting from oneend to the other as the spreader plate passes the middle.

While in FIG. 12 I have shown means by which the electrolytic action onthe work is automatically controlled in response to the dimension of thework, I also contemplate automatically controlling the electrolyticaction in accordance with the electrical resistance of the.

work, such as a wire or filament. Although this may be accomplished inother ways, it may advantageously be done by including the Wire in onearm of a Wheatstone bridge.

Such an arrangement is shown in FIG. 14. In this figure is illustrated abridge in one arm of which the work, such as wire 1, is included. Itwill, of course, 'be understood that the spreader 2, shown in thisfigure, is mounted to be reciprocated as in FIG. 4, while the wire isrotated.

The bridge has three other arms 71, 72 and 73, and in the arms 71 and 72are included equal fixed resistances R and R In the arm 73 is includedan adjustable resistance R The electrolytic circuit includes a source 11of direct current, as before, connected with the spreader and the workby conductors 12 and 13, the latter including the armature 68 of arelay, and a pair of contacts positioned to be bridged by such armature.This armature is moved to closed position by a relay winding 69,connected to the output side of an amplifier 70, and is Ibiased to openposition by a spring 86.

In order to prevent the possibility of any interaction between themonitoring and electrolytic circuits, I preferably employ an alternatingcurrent for the former. A source 74 of alternating current is connectedby conductors 75 and 76 to two opposite corners 77 and 78 of the bridge.The other two opposite corners 79 and 80, are connected by conductors 81and 82 with the control input side of the amplifier 70, supplied withcurrent by a cord and plug 85. The wire 1, being treated, is connectedbetween the corners 77 and of the bridge. Variable condensers C and Care advantageously included in a cross-connection 83 between conductors75 and 76, the mid-point between these condensers being connected by aconductor 74 with the corner 79 of the bridge. This is for the purposeof balancing the reactive components of the alternating current. Acondenser C is also included in the conductor 82.

In operation, the resistance R is set at a point equal to the desiredresistance of the finished work or wire. As long as this resistance isless than that at which R, is set, the bridge will be unbalanced, andalternating current will flow over the circuit 81, 82 to the amplifier,thus holding the relay contacts 68 closed, and permitting theelectrolytic vcurrent to flow through the spreader plate and work. Asthe electrolytic action progresses, the work or wire is graduallyreduced in diameter and its resistance correspondingly increased.Finally, when this resistance reaches the value to which R has been set,the bridge is balanced, no current flows in the circuit 81, 82, and therelay 68 opens, thus interrupting the flow of electrolytic current.

In FIG. 15 is shown a system for controlling the etching action inaccordance with the diameter of the wire, the system comprising a linearmotion transducer which includes a primary coil 91, a pair of secondarycoils 92 and 93 connected in series combination, and an iron slug 94mounted for movement between the primary and secondary coils. Power isfed from an oscillator 95 to primary coil 91 which induces at the outputof the secondary coils a voltage proportional to the position of theslug 94.

The slug is connected to a movable jaw 96 disposed opposite a stationaryjaw 97, wire 1 passing between the jaws so that changes in the diametercause the movable jaw to actuate slug 94. Jaws 96 and 97 are located sothat when there is no wire between them, the slug is positioned abovethe neutral point to prevent the slug from passing through the null. Ifthe slug could pass through the null, the output voltage would increasewith decreasing diameter so that the device would be an electronic wirecutter.

The output from secondary coils 92 and 93 is fed to an amplifier 98where the signal is amplified and fed to a rectifier 99. A fixedresistor 100 and a variable resistor 101 are connected in series acrossa battery 102 to bias the output of rectifier 99 so that, at apredetermined diameter of wire 1, the etching action would stop. Therectifier is connected so that the positive voltage is applied toelectrode 103 and so that the negative voltage is applied to wire 1.Electrode 103 contacts the electrolyte and can be a spreader plate ofthe type previously described.

In operation, as wire 1 passes between jaws 96 and 97, variations in thediameter of the wire move slug 94 to produce an output voltage fromtransducer 90 proportional to the variation in diameter. The outputvoltage is amplified and rectified so that variation in diameter of awire alters the etching voltage in the direction tending to offset suchvariation. Thus, an increase in the diameter of wire 1, as sensed by themovable jaw 96, increases the etching voltage so that the electrolyticaction etches away the increased diameter portion at a greater rate thanthat required for lesser diameter portions. Likewise, a decrease in thediameter of wire 1 decreases the etching voltage.

In operating the system shown in FIG. 15, a problem sometimes occurswhich is best understood with reference to FIG. 16. After several passeshave been made, the diameter of portion 1 is substantially greater thanthat of wire 1, and a tapered portion 104 extends between portions 1and 1. When the sheet of electrolyte flows over the tapered portion 104,there is a tendency for some of the fluid to flow downwardly over thetapered portions so that a greater quantity of liquid flows over portion195. As movable jaw 96 starts to climb the taper, the etching voltage isincreased and thereby causes portion 105 to be necked down, asillustrated in FIG. 16, and to produce an imperfect object.

One way to prevent this is to attenuate the etching voltage and effect amore gradual cutofi. Another way to prevent the necking down isillustrated in FIGS. 17 and 18. As shown in FIG. 17, a pair ofelectrodes 106 and 107 are mounted upon but electrically insulated frommovable jaw 96, the electrodes being insulated from each other andspaced apart longitudinally of wire 1. Dependent upon the direction ofmotion, one of the electrodes is leading and the other is lagging.Electrodes 106 and 107 are connected to a double-pole, double-throwrelay, indicated generally by numeral 108, having a coil 108 connectedto reverse the electrodes from leading to lagging when the lathereverses. Wires 109 are connected to hte output of rectifier 99, thewires being further connected to an electronic thyratron controlswitching system, indicated generally by numeral 110 so that the etchingvoltage is switched, by means of a pair of single-pole, single-throwswitches 110* and 110, from the leading electrode for increasingdiameters to the lagging electrode for decreasing diameters.

Another method of preventing the necking down would be to narrow thestream of electrolyte as it passes across the wire. One way of doingthis is illustrated in FIG. 23 and includes a probe 111 having a centralbore 112 through which the electrolyte flows over wire 1, probe 111being connected to tubing 6. The stationary jaw is also provided with apassage 113 to receive the electrolyte flowing over wire 1.

It sometimes happens that when spreader plates of the types shown inFIGS. 3 and 3 are used, wire 1 moves in an unpredictable fashionrelative to the spreader plate and thereby produces unwanted etchingaction. To prevent this, it is desirable to confine the movement of wire1, in the vicinity of the spreader plate, so that unwanted movement isprevented and higher etching voltages can be employed to increase thecutting rate. Two embodiments for accomplishing this are shown in FIGS.19 and 20. As'shown in FIG. 19, a spreader plate 115 of con ductivematerial, is mounted on a rigid plate 114 of insulating material, plate114 being provided with an elongated slot 114a for adjustably mountingthe same. A jewel rest 116 is mounted beneath the spreader plate 115 onplate 114. Plate 114 has an aperture 117 so that the wire can passbetween the lower edge of spreader plate 115 and the upper surface ofrest 116. Plate 114 is mounted so that rest 116 produces an upwardforce, in the direction of the arrow in FIG. 21, causing wire 1 to passby plate 115 at a point spaced from the longitudinal axis of rotation ofchucks 14. One of the chucks 14 is biased by a tension spring 118 tomaintain wire 1 in engagement with rest 116. With this construction, itis obvious that as the diameter of wire 1 decreases, the distance fromthe upper portion of wire 1 to plate 115 becomes greater.

If it is desired to maintain the distance between wire 1 and thespreader plate constant, the spreader plate can be mounted as shown inFIG. 20. In this embodiment, plate 114 is provided with an invertedV-shaped end 119 which engages wire 1. Plate 114 is mounted oft centerfrom the axis of rotation of chucks 14 and pushes downwardly on wire 1in the direction of the arrow in FIG. 22 so that spring 118 maintainswire 1 in engageemnt with end 119. Thus, the distance between the loweredge of plate 115 and the adjacent surface of wire 1 remains constant.

It has also been found that with a given etchingvoltage and a givenelectrode spacing, the etching action can be controlled in accordancewith the flow rate of the electrolyte. One embodiment for doing this isillustrated in FIG. 24. As shown, wire 1 passes over a fixed jaw 120disposed opposite a movable jaw 121 which engages the upper edge ofwire 1. Jaw 121 is connected to actuate a valve 122 which controls theflow of electrolyte from a reservoir 123 over wire 1. Thus, an increasein the diameter of wire 1 causes an increased flow rate and hence anincreased etching action. Likewise, a decrease in diameter decreases theflow rate and etching action.

Since the etching action is fairly slow, it is desirable under manycircumstances to construct the lathe so that several wires can beconcurrently formed. One embodiment for accomplishing this isillustrated in FIG. 26 and includes a reversible electric motor 124which drives a spindle 125. A pair of carriages 126 and 127 are mountedfor movement along a pair of guides 128. Chucks 14 are mounted oncarriages 126 and 127 in opposed positions and support a plurality ofwires 1 therebetween. Spindle drives gears 129 which are connected torotate worm gears 130 and a pair of idler gears 131. Gears 131 drivegears 132 which rotate chucks 14. A stationary screw 133 cooperates withgears 131) to move the carriages 126 and 127 along guides 128. Each ofwires 1 is electrically insulated from the other wires so that theetching voltages can be controlled for each wire. One manner of doingthis includes constructing carriages 126 and 127 of insulating material,gears 132 and 129 of brass or other suitable metal and gears 131 ofglass fiber or other suitable insulating material. Thus, wires 1 aresupported in a manner electrically insulated from each other so that thevoltage applied to one is not applied to the other. At the end of eachpass, motor 124 is reversed by a pair of limit switches 134 mounted toengage the carriages. Note also in this embodiment that the wires aremoved relative to the spreader plates both longitudinally androtationally, the spreader plates being indicated by the dotted boxes135.

Carriages 126 and 127 can be also driven by a unidirectional motor. Asshown in FIG. 25, a unidirectional motor 136 drives a gear 137 which inturn is meshed with gears 138. Gears 138 are connected to solenoidactuated clutch-brakes 139 and 140, the output of these devices beingconnected to a diiferential indicated generally by numeral 141 having anoutput gear connected to drive spindle 125. Clutch-brakes 139 and arealternately operated in response to actuation of limit switches 134controlled by the position of carriages 126 and 127 so that when, forexample, clutch-brake 139 is actuated, spindle 125 is driven in onedirection and thereby causes the carriages to move along the guides inone direction and when clutch-brake 140 is actuated, the spindle 125 andthe carriages are driven in the opposite directions.

There is shown in FIG. 28 a system for automatically controlling anelectrolyte lathe to concurrently. shape a plurality of wires. Thesystem comprises a power supply 142 connected to a relay system 143 forsupplying power to operate a motor 144, a pump 145, a buzzer 146 to etchthe wires being shaped. An on-ofl? button 147 is connected to the relaysystem 143 and controls the operation of the lathe. After the lathe hasbeen turned on by pressing the on-ofi button and has been loaded byplacing the wires in the proper chucks, a start button 148 is pushed tobegin a production cycle. When the production cycle is complete, thepump is operated to return all the electrolyte which has flowed over thewires to a reservoir and buzzer 146 is turned on to notify the operatorthat the cycle is complete. The buzzer is turned off by actuating a pushbutton 149 connected to the relay system.

When the start button is pressed to begin a cycle, the relay systemconnects the motor to the power supply whereby the motor reciprocatesand rotates the wires relative to the sheets of electrolyte flowing overthe wires. Limit switches 150 are arranged to reverse the direction ofreciprocation at the end of each pass.

The flow of current between the electrode 151, i.e., the associatedspreader plates and wires, is controlled by a suitable etchingcontroller 152. During the first pass, a

1 l relatively low etching voltage is applied to each pair of electrodesto clean the wires. At the end of the first pass, and during the secondpass, a higher etching voltage is applied to etch each wire.

At the end of the second pass and every subsequent pass, the relativemotion and the etching action are stopped and a master stepping switch153 connects the wires, one at a time, to an electronic potentiometer154 which measures the resistance of each wire. A plurality of steppingswitches 155, one for each wire being shaped, are actuated by thepotentiometer so that, when the resistance of each wire increases beyonda predetermined value, the etching voltage is decreased. When thepotentiometer indicates that the resistance of each wire has reached avalue indicative that the shaping of such wire is complete, the steppingswitch associated with such wire goes home and no further etching ofthat wire takes place. When all the stepping switches are home, theproduction cycle is complete and the buzzer goes on.

While several embodiments have been shown, it is obvious that some ofthe details of some can be substituted for some of the details of othersand that the various ways for controlling the electrolytic action can becombined. For example, the etching action can be controlled in acordancewith both the resistance and the diameter of the wire. It will beobvious to those skilled in the art that many changes can be made in thedetails and arrangement of parts without departing from the scope of theinvention as defined in the appended claims.

What is claimed is:

1. An electrolytic lathe comprising work holding means adapted torotatably support a work piece, reservoir means adapted to contain asupply of electrolyte, an inclined spreader plate means having anopening therein for passage of said work piece and capable of causingsaid electrolyte to flow in a sheet over said work piece as said workpiece is being rotated, said spreader plate means being designed andinstalled to provide a sheet of electrolyte over said opening having athickness less than the length of the portion of the article beingtreated, reciprocatory means to produce relative motion between saidwork piece and said spreader plate means so that said electrolytecontacts said work piece at successive portions, and electrical meansadapted to cause current to flow through said electrolyte and said workpiece.

2. An electrolytic lathe for shaping a wire comprising holder means forsupporting said wire, spreader plate means having an opening therein forpassage of said wire and capable of causing an electrolyte to flow in asheet over said wire in a plane transverse to the axis of said wire,said spreader plate means being designed and installed to provide asheet of electrolyte having a thickness substantially less than thelength of the portion of said wire being shaped, drive means forproducing relative rotation between said spreader plate means and saidwire, said driving means being further operative to produce between saidspreader plate means and said wire relative reciprocation in a directionalong said wire, and electrical means adapted to connect said sheet andsaid wire to a source of current.

3. An electrolytic lathe in accordance with claim 2 and additionallyincluding means for varying the flow of current to control theelectrolytic action.

4. An electrolytic lathe in accordance with claim 2 and additionallyincluding means for varying the flow of current to control theelectrolytic action in accordance with the resistance of said wire.

5. An electrolytic lathe for producing a filament having a pair ofterminal leads and a main body extending between said leads comprising apair of chucks adapted to be connected to said leads for rotatablysupporting said filament, drive means for rotating said chucks to rotatesaid filament, spreader plate means having an opening therein for thepassage of said main body and capable of causing a sheet of electrolyteto flow over said main body portion in a plane transverse to saidfilament and being of a thickness less than the length of said mainbody, second drive means for producing relative reciprocation betweensaid filament and said spreader plate means in a direction along saidmain body, and electrical means adapted to connect said filament andsaid sheet to a source of current.

6. Apparatus for electrolytically treating an elongated metallic wirehaving at least two portions of different diameters, comprising holdingmeans for mounting the wire for rotation about its axis, spreader platemeans having an opening therein for passage of said wire and capable ofproducing a continuously flowing sheet of electrolyte disposed in aplane extending transversely across said wire, an electric circuitconnecting said sheet of electrolyte and said wire in series, drivemeans for producing relative longitudinal movement between said spreaderplate means and said wire, and control means adapted to selectivelyconnect said circuit to a source of current so that current flowsthrough said electrolyte and said wire only when said electrolytecontacts that portion of said wire of a certain diameter.

7. Apparatus for producing an elongated metallic wire element having atleast one portion of a predetermined diameter and at least one otherportion of a diameter less than that of said first portion, comprisingholding means for mounting said wire for rotation about its axis,spreader plate means having an opening therein for the passage of saidwire and capable of producing a continuously flowing sheet ofelectrolyte disposed in a plane extending transversely across said wire,drive means for producing relative longitudinal movement between saidspreader plate means and said wire longitudinally of said wire, so thatsaid sheet is caused to impinge against successive portions of saidwire, and an electric circuit adapted to connect said flowing sheet ofelectrolyte and said wire in series to a source of current and includingmeans to interrupt said connection so that current flows only when saidelectrolyte impinges against that portion of the wire of smallerdiameter.

8. Apparatus for electrolytically shaping an elongated metal articlecomprising spreader plate means having an opening therein for passage ofsaid article and capable of producing a continuously flowing sheet ofelectrolyte disposed in a plane extending transversely across the axisof the article to be shaped, a source of current, a circuit connectingsaid flowing sheet of electrolyte and said article in series, drivemeans for producing relative movement between said spreader plate andsaid article longitudinally of the latter, so that said flowing sheetfrom said spreader plate is caused to impinge against successiveportions of said article, as such movement takes plate, and means forautomatically interrupting said circuit at certain definite points insuch movement.

9. Apparatus for electrolytically shaping an elongated metal articlecomprising spreader plate means having an opening therein for passage ofsaid article for producing a continuously flowing sheet of electrolytedisposed in a plane extending transversely across the axis of thearticle to be shaped, a source of current, drive means for producingrelative travel between said spreader plate means and said articlelongitudinally of the latter so that said flowing sheet from saidspreader plate is caused to impinge successively on different parts ofsaid article as such travel takes place, and electrical means forautomatically connecting said source in a series circuit with saidflowing sheet and article during certain definite portions of suchtravel, and for automatically interrupting said circuit during otherportions of such travel.

10. Apparatus for electrolytically shaping an elongated metallic wireelement comprising holding means supporting said element, spreader platemeans having an opening therein for passage of said wire element andcapable of producing a continuously flowing sheet of electrolyte in aplane extending transversely across said element, drive means forproducing relative rotation and axial movement between said spreaderplate means and said element sothat said sheet from said spreader plateimpinges against successive portions of said element as such movementoccurs, means for causing an electric current to pass serially throughsaid flowing sheet and said element, and means for automatically varyingsaid current to shape said element.

References Cited by the Examiner UNITED STATES PATENTS 480,186 8/1892Elmore et a1. 204-217 X 1,562,846 11/1925 Payne 204-218 X 1,773,1358/1930 Flanzer 204-212 X 2,068,352 1/1937 Schlacks 204-141 1/ 1943Hogaboom 204-141 2/ 1946 Venable 204-141 10/1950 Rudorff 204-143 10/1952 Pendleton 118-325 9/1956 Pullen 204-211 3/ 1957 Korbelak 204-1416/1957 Eigler 204-143 3/1958 Barry 204-143 2/1962 Burke et a1. 118-325FOREIGN PATENTS 10/ 1939 Germany.

2/ 1897 Great Britain.

15 WINSTON A. DOUGLAS, Primary Examiner.

JOHN R. SPECK, JOHN H. MACK, Examiners.

1. AN ELECTROLYTIC LATHE COMPRISING WORK HOLDING MEANS ADAPTED TOROTABLY SUPPORT A WORK PIECE, RESERVOIR MEANS ADAPTED TO CONTAIN ASUPPLY OF ELECTROLYTE, AN INCLINED SPREADER PLATE MEANS HAVING ANOPENING THEREIN FOR PASSAGE OF SSAID WORK PIECE AND CAPABLE OF CAUSINGSAID ELECTROLYTE TO FLOW IN A SHEET OVER SAID WORK PIECE AS SAID WORKPIECE IS BEING ROTATED, SAID SPREADER PLATE MEANS BEING DESIGNED ANDINSTALLED TO PROVIDE A SHEET OF ELECTROLYTE OVER SAID OPENING HAVING ATHICKNESS LESS THAN THE LENGTH OF THE PORTION OF THE ARTICLE BEINGTREATED, RECIPROCATORY MEANS TO PRODUCE RELATIVE MOTION BETWEEN SAIDWORK PIECE AND SAID SPREADER PLATE MEANS SO THAT SAID ELECTROLYTECONTACTS SAID WORK PIECE AT SUCCESSIVE PORTIONS, AND ELECTRICAL MEANSADAPTED TO CAUSE CURRENT TO FLOW THROUGH SAID ELECTROLYTE AND SAID WORKPIECE.